OLDHAM (P.)Pill Boxes on the Western Front: A Guide to the Design, Construction & Use of Concrete Pill Boxes 1914-1918.

ORPEN (Col. Neil) & MARTIN (Lt.-Gen. H.J.)South African Forces World War II (Vol. VIII, Parts I & II): Salute the Sappers. Part I: The Formation of the South African Engineer Corps & its Operations in East Africa & the Middle East to the Battle of Alamein. Part II: The Operations of the South African Engineer Corps in the North African & Italian Theatres of War from the Battle of El Alamein to the end of WW2.